The present disclosure relates to electronic devices containing chemically sensitive thin-film transistors (TFTs). The devices can contain one or more different types of transistors, and are useful in the detection, identification, and/or quantification of compounds, such as volatile compounds associated with explosive materials.
TFTs are generally composed of, on a substrate, an electrically conductive gate electrode, source and drain electrodes, an electrically insulating gate dielectric layer which separate the gate electrode from the source and drain electrodes, and a semiconducting layer which is in contact with the gate dielectric layer and bridges the source and drain electrodes. Their performance can be determined by the field effect mobility and the current on/off ratio of the overall transistor.
Organic thin-film transistors (OTFTs) can be fabricated using low-cost solution-based patterning and deposition techniques, such as spin coating, solution casting, dip coating, stencil/screen printing, flexography, gravure, offset printing, ink jet-printing, micro-contact printing, and the like. This low cost permits OTFTs to be used in applications where disposal of the electronic device may be useful.
The detection of explosive compounds is desirable in homeland security applications and other protective functions. Explosive compounds typically contain nitrogen and include trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX), and pentaerythritol tetranitrate (PETN). Some chemical warfare agents also contain nitrogen atoms, such as some blister agents, nerve agents, and incapacitating agents.
The identification of certain compounds from other similar compounds is also desirable in several household and industrial applications. For example, a chemical sensor can indicate an excessive amount of carbon monoxide. The presence or absence of a particular chemical can also be used to control some industrial processes. Detecting particular contaminants or byproducts is also useful for quality control purposes.
It would be desirable to use the low-cost possibilities of OTFTs to perform some of the chemical sensing functions mentioned above.